Modern printing devices such as printers, copiers, and fax machines use certain materials that are consumed in the operation of the device. Examples of such materials include toner and a print medium, such as paper. The device manufacturer and other manufacturers will normally provide toner in a disposable cartridge that can be discarded when the contained toner is consumed. A new cartridge is then installed in the printing device.
For many users, the replacement of a toner cartridge represents both an inconvenience in time and an expense to purchase a new toner cartridge or refill the old one. Consequently, users appreciate being able to track toner usage and have an indication of the amount of toner remaining in a current toner cartridge. Some relatively sophisticated toner cartridges include a sensor that will actually sense the quantity of toner remaining in the cartridge with the result being reported to a user. Such a sensor, however, clearly adds expense and complexity to the printer. Therefore, other printing systems have taken a different approach, attempting to estimate the quantity of toner remaining in a cartridge. Such estimation techniques are typically based on the average behavior of that particular make and model of the printer, with each printer of that make and model estimating toner usage using the same parameters.
However, the rate at which toner is used in a printer is a function of many different variables, many of which are not specific to the make and model of the printer. For example, some of these variables depend upon the ambient environment in which the printer is deployed and used. Such environmental variables include, for example, temperature, humidity, altitude, etc. Other variables that bear on the rate of toner consumption depend on the kind of usage the printer experiences. Such usage variables include, for example, average print job length, mix of color versus monochrome print jobs, wear or age of components, etc. Other variables that bear on the rate of toner consumption result from variations that exist from printer to printer due to tolerances in manufacturing processes. Such printer-specific variables include, for example, sensor accuracies, component variations, etc.
As a result of these many different variables that help determine the rate at which toner is consumed, the actual toner consumption rate will vary, perhaps widely, from printer to printer. This is true even if the printers in question are of the same make and model. Therefore, if a printer relies on some form of open loop analytical computation to estimate toner remaining, as opposed to direct measurement from a sensor, the computation may be accurate for the average printer performance, but will not be accurate for many individual printers. Consequently, traditional methods of estimating toner usages based on the make and model of the printer have demonstrated a relatively low level of accuracy.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.